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Re: [Qemu-devel] [PATCH 0/4] s390: Allow hotplug of s390 CPUs
From: |
Christian Borntraeger |
Subject: |
Re: [Qemu-devel] [PATCH 0/4] s390: Allow hotplug of s390 CPUs |
Date: |
Mon, 9 Nov 2015 16:55:51 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 |
Am 09.11.2015 um 16:37 schrieb Christian Borntraeger:
> Am 09.11.2015 um 16:35 schrieb Christian Borntraeger:
>> Am 09.11.2015 um 16:28 schrieb Andreas Färber:
>>> Hi,
>>>
>>> Am 09.11.2015 um 16:17 schrieb Matthew Rosato:
>>>> To subsequently hotplug a CPU:
>>>>
>>>> Issue 'cpu-add <id>' from qemu monitor, or use virsh setvcpus --count <n>
>>>> <domain>, where <n> is the total number of desired guest CPUs.
>>>
>>> What exactly is still missing for you to use the standard device_add?
>>>
>>> Last time I checked (a while ago...) some patches were stuck on the x86
>>> side, and I don't recall hearing any feedback from the s390x side in my
>>> KVM Forum CPU hotplug session.
>>
>> libvirt uses "cpu-add" unconditionally for hotplugging, so we certainly
>> want to support that.
>
> Sorry, hit send too early. I assume you want us to support device_add of
> a CPU in addition to that. Correct?
I just did a quick test with Matts patch.
after applying
diff --git a/qom/cpu.c b/qom/cpu.c
index fb80d13..8152744 100644
--- a/qom/cpu.c
+++ b/qom/cpu.c
@@ -360,7 +360,7 @@ static void cpu_class_init(ObjectClass *klass, void *data)
* Reason: CPUs still need special care by board code: wiring up
* IRQs, adding reset handlers, halting non-first CPUs, ...
*/
- dc->cannot_instantiate_with_device_add_yet = true;
+// dc->cannot_instantiate_with_device_add_yet = true;
}
static const TypeInfo cpu_type_info = {
I was able to use
device_add s390-cpu
but no comprehensive testing was done.
I was even able to add more cpus than maxcpus, but the guest could not
make use of it. Fix is probably easy. But in general it looks like
that we _could_ enable device_add for CPUs as soon as others are ready
as well.
Matt, do you agree?
Christian
- [Qemu-devel] [PATCH 0/4] s390: Allow hotplug of s390 CPUs, Matthew Rosato, 2015/11/09
- [Qemu-devel] [PATCH 1/4] s390x/cpu: Cleanup init in preparation for hotplug, Matthew Rosato, 2015/11/09
- [Qemu-devel] [PATCH 2/4] s390x/cpu: Set initial CPU state in common routine, Matthew Rosato, 2015/11/09
- [Qemu-devel] [PATCH 3/4] s390x/cpu: Add function to set CPU state, Matthew Rosato, 2015/11/09
- [Qemu-devel] [PATCH 4/4] s390x/cpu: Allow hotplug of CPUs, Matthew Rosato, 2015/11/09
- Re: [Qemu-devel] [PATCH 0/4] s390: Allow hotplug of s390 CPUs, Andreas Färber, 2015/11/09